Changes in gene expression are at the heart of many cellular responses to internal or external stimuli. In the case of disease, such changes may be causative or secondary in response to the disease process. Spotted cDNA microarrays are emerging as a powerful tool for large-scale analysis of these gene expression patterns. With NHLBI support, The Jackson Laboratory (TJL) staff and their collaborators have used genetic approaches to study atherosclerosis, lipid disorders, hypertension, anemia, hemopoietic stem cell function, lung diseases, and sleep disorders, and made major contributions to understanding the genes underlying the models studied. cDNA microarrays will provide further insights into the diseases they study, by enhancing QTL analysis, elucidation of regulatory networks, and the monitoring of disease progression. To enable TJL NHLBI-funded researchers and their colleagues to use expression arrays in their research programs, we will expand an existing gene expression array service that will be integrated into TJL's Scientific Services. We will also make use of existing strengths at TJL in biostatistics and bioinformatics in further developing this service. Specifically, we will increase the operating capacity of an existing gene expression service encompassing high quality production, processing, and analysis of DNA microarrays to accommodate NBLBI-funded projects. We will improve the reliability of the generated data by using spotted long oligo-nucleotides instead of cDNA libraries. We will augment the service by offering expression analysis of RNA samples obtained by laser-capture micro-dissection. TJL has recognized strengths in bioinformatics and the statistical analysis of genetic and gene expression data. This will allow us to expertly and efficiently analyze array data and disseminate them to the scientific community. Through lectures and training sessions at TJL courses and workshops, and our visiting investigator program, we will promote this new research field. One of TJL's three missions is to provide resources to the scientific community. The Laboratory has a long history of resource sharing and has established distribution channels and bioinformatics support. Experimental data, novel analysis methods, reference standards, and array materials will be made public, and shared without undue restrictions. Processed data will be incorporated into the mouse Gene Expression Database (GXD).